org.elasticsearch.index.engine

Class ShadowEngine

java.lang.Object

org.elasticsearch.index.engine.Engine

org.elasticsearch.index.engine.ShadowEngine

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class ShadowEngine
extends Engine

ShadowEngine is a specialized engine that only allows read-only operations on the underlying Lucene index. An IndexReader is opened instead of an IndexWriter. All methods that would usually perform write operations are no-ops, this means: - No operations are written to or read from the translog - Create, Index, and Delete do nothing - Flush does not fsync any files, or make any on-disk changes In order for new segments to become visible, the ShadowEngine may perform stage1 of the traditional recovery process (copying segment files) from a regular primary (which uses InternalEngine) Notice that since this Engine does not deal with the translog, any Engine.get(Get, Function) request goes directly to the searcher, meaning it is non-realtime.

Nested Class Summary

Nested classes/interfaces inherited from class org.elasticsearch.index.engine.Engine

Engine.CommitId, Engine.Delete, Engine.DeleteResult, Engine.EventListener, Engine.Get, Engine.GetResult, Engine.Index, Engine.IndexResult, Engine.IndexThrottle, Engine.NoOpLock, Engine.Operation, Engine.Result, Engine.Searcher, Engine.SyncedFlushResult, Engine.Warmer

Field Summary

Fields

Modifier and Type	Field and Description
static TimeValue	DEFAULT_NONEXISTENT_INDEX_RETRY_WAIT
static java.lang.String	NONEXISTENT_INDEX_RETRY_WAIT how long to wait for an index to exist

Fields inherited from class org.elasticsearch.index.engine.Engine

deletionPolicy, engineConfig, eventListener, failedEngine, failEngineLock, isClosed, lastWriteNanos, logger, readLock, rwl, shardId, store, SYNC_COMMIT_ID, writeLock

Constructor Summary

Constructors

Constructor and Description
ShadowEngine(EngineConfig engineConfig)

Method Summary

Modifier and Type	Method and Description
org.apache.lucene.index.IndexCommit	acquireIndexCommit(boolean flushFirst) Snapshots the index and returns a handle to it.
void	activateThrottling() Request that this engine throttle incoming indexing requests to one thread.
protected void	closeNoLock(java.lang.String reason, java.util.concurrent.CountDownLatch closedLatch) Method to close the engine while the write lock is held.
void	deactivateThrottling() Reverses a previous Engine.activateThrottling() call.
Engine.DeleteResult	delete(Engine.Delete delete) Perform document delete operation on the engine
Engine.CommitId	flush() Flushes the state of the engine including the transaction log, clearing memory and persisting documents in the lucene index to disk including a potentially heavy and durable fsync operation.
Engine.CommitId	flush(boolean force, boolean waitIfOngoing) Flushes the state of the engine including the transaction log, clearing memory.
void	forceMerge(boolean flush, int maxNumSegments, boolean onlyExpungeDeletes, boolean upgrade, boolean upgradeOnlyAncientSegments) Triggers a forced merge on this engine
Engine.GetResult	get(Engine.Get get, java.util.function.Function<java.lang.String,Engine.Searcher> searcherFacotry)
long	getIndexBufferRAMBytesUsed() How much heap is used that would be freed by a refresh.
long	getIndexThrottleTimeInMillis() Returns the number of milliseconds this engine was under index throttling.
protected org.apache.lucene.index.SegmentInfos	getLastCommittedSegmentInfos()
protected org.apache.lucene.search.SearcherManager	getSearcherManager()
Translog	getTranslog() returns the translog for this engine
Engine.IndexResult	index(Engine.Index index) Perform document index operation on the engine
boolean	isThrottled() Returns the true iff this engine is currently under index throttling.
Engine	recoverFromTranslog() Performs recovery from the transaction log.
void	refresh(java.lang.String source) Synchronously refreshes the engine for new search operations to reflect the latest changes.
java.util.List<Segment>	segments(boolean verbose) The list of segments in the engine.
Engine.SyncedFlushResult	syncFlush(java.lang.String syncId, Engine.CommitId expectedCommitId) Attempts to do a special commit where the given syncID is put into the commit data.
void	writeIndexingBuffer() Called when our engine is using too much heap and should move buffered indexed/deleted documents to disk.

Methods inherited from class org.elasticsearch.index.engine.Engine

acquireSearcher, close, commitStats, config, ensureOpen, failEngine, flushAndClose, forceMerge, getFromSearcher, getLastWriteNanos, getMergeStats, getSegmentInfo, guardedRamBytesUsed, isMergedSegment, isRecovering, maybeFailEngine, newSearcher, onSettingsChanged, readLastCommittedSegmentInfos, refreshNeeded, segmentReader, segmentsStats, writerSegmentStats

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NONEXISTENT_INDEX_RETRY_WAIT

public static final java.lang.String NONEXISTENT_INDEX_RETRY_WAIT

how long to wait for an index to exist

See Also:

Constant Field Values

DEFAULT_NONEXISTENT_INDEX_RETRY_WAIT

public static final TimeValue DEFAULT_NONEXISTENT_INDEX_RETRY_WAIT

Constructor Detail

ShadowEngine

public ShadowEngine(EngineConfig engineConfig)

Method Detail

index

public Engine.IndexResult index(Engine.Index index)

Description copied from class: Engine

Perform document index operation on the engine

Specified by:

index in class Engine

Parameters:

index - operation to perform

Returns:

Engine.IndexResult containing updated translog location, version and document specific failures Note: engine level failures (i.e. persistent engine failures) are thrown

delete

public Engine.DeleteResult delete(Engine.Delete delete)

Description copied from class: Engine

Perform document delete operation on the engine

Specified by:

delete in class Engine

Parameters:

delete - operation to perform

Returns:

Engine.DeleteResult containing updated translog location, version and document specific failures Note: engine level failures (i.e. persistent engine failures) are thrown

syncFlush

public Engine.SyncedFlushResult syncFlush(java.lang.String syncId,
                                          Engine.CommitId expectedCommitId)

Description copied from class: Engine

Attempts to do a special commit where the given syncID is put into the commit data. The attempt succeeds if there are not pending writes in lucene and the current point is equal to the expected one.

Specified by:

syncFlush in class Engine

Parameters:

syncId - id of this sync

expectedCommitId - the expected value of

Returns:

true if the sync commit was made, false o.w.

flush

public Engine.CommitId flush()
                      throws EngineException

Description copied from class: Engine

Flushes the state of the engine including the transaction log, clearing memory and persisting documents in the lucene index to disk including a potentially heavy and durable fsync operation. This operation is not going to block if another flush operation is currently running and won't write a lucene commit if nothing needs to be committed.

Specified by:

flush in class Engine

Returns:

the commit Id for the resulting commit

Throws:

EngineException

flush

public Engine.CommitId flush(boolean force,
                             boolean waitIfOngoing)
                      throws EngineException

Description copied from class: Engine

Flushes the state of the engine including the transaction log, clearing memory.

Specified by:

flush in class Engine

Parameters:

force - if true a lucene commit is executed even if no changes need to be committed.

waitIfOngoing - if true this call will block until all currently running flushes have finished. Otherwise this call will return without blocking.

Returns:

the commit Id for the resulting commit

Throws:

EngineException

forceMerge

public void forceMerge(boolean flush,
                       int maxNumSegments,
                       boolean onlyExpungeDeletes,
                       boolean upgrade,
                       boolean upgradeOnlyAncientSegments)
                throws EngineException

Description copied from class: Engine

Triggers a forced merge on this engine

Specified by:

forceMerge in class Engine

Throws:

EngineException

get

public Engine.GetResult get(Engine.Get get,
                            java.util.function.Function<java.lang.String,Engine.Searcher> searcherFacotry)
                     throws EngineException

Specified by:

get in class Engine

Throws:

EngineException

getTranslog

public Translog getTranslog()

Description copied from class: Engine

returns the translog for this engine

Specified by:

getTranslog in class Engine

segments

public java.util.List<Segment> segments(boolean verbose)

Description copied from class: Engine

The list of segments in the engine.

Specified by:

segments in class Engine

refresh

public void refresh(java.lang.String source)
             throws EngineException

Description copied from class: Engine

Synchronously refreshes the engine for new search operations to reflect the latest changes.

Specified by:

refresh in class Engine

Throws:

EngineException

acquireIndexCommit

public org.apache.lucene.index.IndexCommit acquireIndexCommit(boolean flushFirst)
                                                       throws EngineException

Description copied from class: Engine

Snapshots the index and returns a handle to it. If needed will try and "commit" the lucene index to make sure we have a "fresh" copy of the files to snapshot.

Specified by:

acquireIndexCommit in class Engine

Parameters:

flushFirst - indicates whether the engine should flush before returning the snapshot

Throws:

EngineException

getSearcherManager

protected org.apache.lucene.search.SearcherManager getSearcherManager()

Specified by:

getSearcherManager in class Engine

closeNoLock

protected void closeNoLock(java.lang.String reason,
                           java.util.concurrent.CountDownLatch closedLatch)

Description copied from class: Engine

Method to close the engine while the write lock is held. Must decrement the supplied when closing work is done and resources are freed.

Specified by:

closeNoLock in class Engine

getLastCommittedSegmentInfos

protected org.apache.lucene.index.SegmentInfos getLastCommittedSegmentInfos()

Specified by:

getLastCommittedSegmentInfos in class Engine

getIndexBufferRAMBytesUsed

public long getIndexBufferRAMBytesUsed()

Description copied from class: Engine

How much heap is used that would be freed by a refresh. Note that this may throw AlreadyClosedException.

Specified by:

getIndexBufferRAMBytesUsed in class Engine

writeIndexingBuffer

public void writeIndexingBuffer()

Description copied from class: Engine

Called when our engine is using too much heap and should move buffered indexed/deleted documents to disk.

Specified by:

writeIndexingBuffer in class Engine

activateThrottling

public void activateThrottling()

Description copied from class: Engine

Request that this engine throttle incoming indexing requests to one thread. Must be matched by a later call to Engine.deactivateThrottling().

Specified by:

activateThrottling in class Engine

deactivateThrottling

public void deactivateThrottling()

Description copied from class: Engine

Reverses a previous Engine.activateThrottling() call.

Specified by:

deactivateThrottling in class Engine

isThrottled

public boolean isThrottled()

Description copied from class: Engine

Returns the true iff this engine is currently under index throttling.

Specified by:

isThrottled in class Engine

See Also:

Engine.getIndexThrottleTimeInMillis()

getIndexThrottleTimeInMillis

public long getIndexThrottleTimeInMillis()

Description copied from class: Engine

Returns the number of milliseconds this engine was under index throttling.

Specified by:

getIndexThrottleTimeInMillis in class Engine

recoverFromTranslog

public Engine recoverFromTranslog()
                           throws java.io.IOException

Description copied from class: Engine

Performs recovery from the transaction log. This operation will close the engine if the recovery fails.

Specified by:

recoverFromTranslog in class Engine

Throws:

java.io.IOException